Corrosion Protection Properties Of Epoxy Research Articles

Electrochemical analysis of silane incorporated sodium dodecylbenzene sulphonate: zinc sulphate pre-treatment on mild steel and its effect on epoxy coating performance

ABSTRACT Variation of surface chemical energy and its effects on adhesion strength and corrosion protection properties of epoxy coatings of mild steel substrates were studied. Results indicated that pre-treatment with a mixture of 3-glycidoxypropyltrimethoxysilane, sodium dodecylbenzene sulphonates and zinc sulphate inhibitors enhanced the corrosion protection properties of epoxy coating when compared to untreated substrates. The formation of a compact insoluble layer of zinc hydroxide/oxide together with SDBS complex on the mild steel surface was found to affect the adhesion properties and resistance towards cathodic/anodic delamination of epoxy coating. This was primarily caused by the formation of strong interfacial interaction and increased in surface passivation. The findings suggested, adhesion alone plays a little part in preventing underfilm corrosion. The underfilm corrosion activities are determined by surface passivity towards corrosion reactions.

Investigation of Anticorrosion and Mechanical Properties of Azole Functionalized Graphene Oxide Encapsulated Epoxy Coatings on Mild Steel

Improvement of the corrosion protection properties of epoxy coatings on mild steel has been carried out by incorporating the imidazole modified graphene oxide (GO). Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the graphene oxide and functionalized graphene oxide (fGO). The protective performance of the functionalized GO with epoxy-fGO composite coating against corrosion was studied by electrochemical techniques and pull off adhesion test. The electrochemical impedance spectroscopic measurements showed high film resistance, charge transfer resistance with low capacitance for the epoxy-fGO coatings compared to neat epoxy coatings. SECM analysis showed less current distribution (0.5–2.3 I/nA) for fGO-grafted composite coatings compared to neat epoxy coatings (2–10 I/nA). The surface morphological analysis of epoxy-fGO composite coatings was done by field emission scanning electron microscopy with energy-dispersive X-ray analysis and X-ray diffraction (FE-SEM/EDX). Mechanical properties of the coatings were also found to be improved in the presence of modified GO nanoparticles in adhesive measurement. Thus, the epoxy-fGO coatings can enhance the adhesion strength and corrosion protection performance on mild steel.

Self-unfolded graphene for corrosion protection

Inevitable crumpling and folding of graphene in coating matrix restricts the enhancement of corrosion protection properties of graphene-based coatings. Herein, reduced graphene oxide with self-unfolded morphology (S-rGO) and crumpled morphology (C-rGO) were prepared. Compared with C-rGO, S-rGO exhibits a higher performance in enhancing the corrosion protection properties of epoxy coating because S-rGO possesses larger effective aspect ratio and projected area in the direction perpendicular to the diffusion path of aggressive species so that its impermeable domains can force aggressive species to overcome the coating matrix via migrating along longer diffusion paths.

Evaluation of Mechanical Properties and Corrosion Protection Performance of Surface Modified Nano-alumina Encapsulated Epoxy Coated Mild Steel

The incorporation of imidazole-modified nano-alumina on the corrosion protection properties of epoxy coating on mild steel was studied by electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) in 3.5% NaCl solution. The dispersability of the alumina nanoparticles was greatly improved by the surface modification using imidazole in the epoxy matrix. The imidazole-modified nanoparticle was analyzed by Fourier transform infrared spectroscopy. Both EIS and SECM studies confirmed that the corrosion resistance is higher for the alumina–epoxy nanocomposite coated steel than that of the pure epoxy-coated steel. It is evidenced that alumina–epoxy nanocomposite coated mild steel has higher charge transfer resistance values, 156,344 Ω cm2, compared to pure epoxy coated mild steel, 79,546 Ω cm2, at 40 days of immersion. The modified nanoparticles enhanced the adhesive properties of the coatings. Possible chemical interactions between epoxy matrix and surface-modified alumina nanoparticles in nanocomposites cause high protection properties and ionic resistances. FE-SEM/EDX analysis showed the presence of Fe, Al, and O in the corrosion products. Hardness and tensile strength measurements showed that the improved mechanical properties were noticed for alumina–epoxy nanocomposite coated mild steel.

Synthesis and characterization of polyaniline tailored graphene oxide quantum dot as an advance and highly crystalline carbon-based luminescent nanomaterial for fabrication of an effective anti-corrosion epoxy system on mild steel

Abstract For decades the zinc chromate and zinc phosphate pigments have been utilized as the most popular anti-corrosive pigments in the anti-corrosive organic coatings formulations. However, these pigments include heavy and toxic zinc and chrome metals, causing serious risks for the human health and ecosystem. Therefore, demands for finding less toxic and more environmentally friendly alternatives are extremely in progress in recent years. In recent years, the carbon based nanomaterials, such as graphene and graphene oxide, have drawn significant attention of the researchers and scientist for making polymer composites with superior anti-corrosion properties. In this study a well crystalized single atom layered structure graphene oxide quantum dot (GOQD) with lateral dimension, ranging from 2 to 20 nm, was synthesized through a bottom-up” method by direct pyrolyzing of citric acid and then functionalized by polyaniline (PAni) through a rapid-mixture polymerization procedure. The morphology and chemistry of the GOQD-PAni were characterized through atomic force microscopy (AFM), high resolution-transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction analysis (XRD) and photo-luminescent (PL) technique. The effect of GOQD-PAni on the corrosion protection properties of epoxy coating was investigated by electrochemical impedance spectroscopy and salt spray test. Results confirmed that both barrier and inhibitive action of epoxy coating were significantly enhanced in the presence of GOQD-PAni. The fine GOQD-PAni well dispersed in the epoxy matrix, filled the pores and defects and blocked the diffusion pathways.

The effect of nanoporous silica aerogel on corrosion protection properties of epoxy coatings on carbon steel

In this paper, due to special properties of aerogels such as ultra-low density and hydrophobic nature of aerogels, this nanomaterial was used as anticorrosive pigments. Silica aerogel was dispersed in epoxy resin by using sonication method. The dispersion of nanoparticles were characterized by transmission electron microscopy. The anticorrosive properties of these coatings were investigated by salt-spray and electrochemical impedance spectroscopy methods in a 3.5 wt % NaCl solution. Impedance parameters showed a decrease in coating resistance over immersion time. Results indicated that epoxy coatings containing nano silica aerogel could significantly increase the corrosion resistance of composite coatings compared to those of pure epoxy and the highest value was obtained for 0.5% aerogel nanocomposite coatings after 160 days immersion. Pull off adhesion test showed the highest value of adhesion was related to coating containing 0.5% aerogel. According to salt-spray methods, it was found that the best results were obtained with coatings containing 0.5 and 1 wt % of silica aerogel.

Evaluation of Corrosion Protection for Epoxy and Urethane Coating by EIS under Various Cyclic Corrosion Tests

Protective coatings play an important role in the protection of metallic structures against corrosive environment. The main function of anticorrosive coating is to prevent the materials from corrosive agents, such as water, oxygen and ions. In the study, the corrosion protection properties of urethane and epoxy coating systems were evaluated using EIS methods exposed to the corrosion acceleration test such as Norsok M501, Prohesion and hygrothermal cyclic test. AFM analysis of the coating systems was carried out to monitor the change of roughness of coatings. Urethane coating system was more stable than the epoxy coating under given cyclic conditions. Water uptake into the urethane coatings was less than that into the epoxy coating. The urethane coating system showed better corrosion protection than epoxy coating system based on the changes of the impedance modulus at low frequency region with exposure time. Consequently, the corrosion protection properties of the epoxy and urethane coatings was well correspond with their surface roughness changes and water uptakes.